Showing posts with label permafrost. Show all posts
Showing posts with label permafrost. Show all posts

Friday, October 23, 2009

Arctic CO2 Sequestration


The number quoted in the headline is rather surprising, but the text brings it back down to a more convincing 10 to 15%. This is still surprising. Natural land based CO2 sequestration happens in the Arctic and also in peat bogs or swamps world wide where oxygen is squeezed out of the decaying biomass.


Everywhere else CO2 is tied up in the living biomass but is recycling usually over a centuries. Recall that most carbon is tied up in soils and wood.


So besides the oceans absorbing CO2 and converting it into limestone for instance, land uses these two mechanisms to lock up surplus CO2.


I have already posted that the source of increasing CO2 in a post warming world was permafrost carbon release. We now understand that the Holocene is in the business of seeing off the remnants of the ice age. We can therefore anticipate that over the next 10,000 years, that at some point a warming climate will be able to actually warm the Arctic enough to provide a warm enough climate to allow the permafrost to even disappear. I think it is barely possible once the Sahara is fully reforested.


Such a world will likely transfer that permafrost carbon to that forest.


The take home lesson is that a warming climate is a natural generator of CO2 surplus to the biome’s ability to quickly absorb it. The warmer it gets, the more CO2 we will have to deal with.


Of course, this suggests that if the greenhouse gas theory has credence, then any greenhouse warming will have a huge multiplier effect. In short, an increase in anthropogenic CO2 causes an increment of global warming which then causes a major increment of CO2 release in the Arctic, which then causes an additional increase in global warming.


The good news is that if any such effect is real its magnitude continues to shrink as we better understand the various factors.


In fact we can make a rather important statement. This is a runaway feedback process. Once underway it must run to exhaustion until almost all the available CO2 is stripped from the Arctic. This also means that it could have been triggered many times by large volcanic CO2 release. I do not think that the geology quite supports such a scenario.


Therefore, geological work may be able to place upper bounds on the CO2 greenhouse effect that are much lower than presently been accepted.


In short, the tools exist that may make it possible to even outright disprove the CO2 hypothesis or come so close in terms of an upper bound as to render it meaningless.

Oct 15, 2009


Arctic now traps 25 percent of world's carbon – but that could change


The arctic could potentially alter the Earth's climate by becoming a possible source of global atmospheric carbon dioxide. The arctic now traps or absorbs up to 25 percent of this gas but climate change could alter that amount, according to a study published in the November issue of Ecological Monographs.


In their review paper, David McGuire of the U.S. Geological Survey and the University of Alaska at Fairbanks and his colleagues show that the Arctic has been a carbon sink since the end of the last Ice Age, which has recently accounted for between zero and 25 percent, or up to about 800 million metric tons, of the global carbon sink. On average, says McGuire, the Arctic accounts for 10–15 percent of the Earth's carbon sink. But the rapid rate of climate change in the Arctic – about twice that of lower latitudes – could eliminate the sink and instead, possibly make the Arctic a source of carbon dioxide.


"This study is another example of the important role played by USGS and its partners in providing the scientific research that must be the backbone of any actions related to climate change," said Secretary of the Interior Ken Salazar.


Carbon generally enters the oceans and land masses of the Arctic from the atmosphere and largely accumulates in permafrost, the frozen layer of soil underneath the land's surface.


Unlike active soils, permafrost does not decompose its carbon; thus, the carbon becomes trapped in the frozen soil. Cold conditions at the surface have also slowed the rate of organic matter decomposition, McGuire says, allowing Arctic carbon accumulation to exceed its release.


But recent warming trends could change this balance. Warmer temperatures can accelerate the rate of surface organic matter decomposition, releasing more carbon dioxide into the atmosphere. Of greater concern, says McGuire, is that the permafrost has begun to thaw, exposing previously frozen soil to decomposition and erosion. These changes could reverse the historical role of the Arctic as a sink for carbon dioxide.


"In the short term, warming temperatures could release more Arctic carbon to the atmosphere," says McGuire. "And with permafrost thawing, there will be more available carbon to release."


On the scale of a few decades, the thawing permafrost could also result in a more waterlogged Arctic, says McGuire, a situation that could encourage the activity of methane-producing organisms. Currently, the Arctic is a substantial source of methane to the atmosphere: as much as 50 million metric tons of methane are released per year, in comparison to the 400 million metric tons of carbon dioxide the Arctic stores yearly. But methane is a very potent greenhouse gas – about 23 times more effective at trapping heat than carbon dioxide on a 100-year time scale. If the release of Arctic methane accelerates, global warming could increase at much faster rates.


"We don't understand methane very well, and its releases to the atmosphere are more episodic than the exchanges of carbon dioxide with the atmosphere," says McGuire. "It's important to pay attention to methane dynamics because of methane's substantial potential to accelerate global warming."


But uncertainties still abound about the response of the Arctic system to climate change. For example, the authors write, global warming may produce longer growing seasons that promote plant photosynthesis, which removes carbon dioxide from the atmosphere. Also, the expansion of shrubs in tundra and the movement of treeline northward could sequester more carbon in vegetation. However, increasingly dry conditions may counteract and overcome these effects. Similarly, dry conditions can lead to increased fire prevalence, releasing even more carbon.


McGuire contends that only specific regional studies can determine which areas are likely to experience changes in response to climate change.


"If the response of the arctic carbon cycle to climate change results in substantial net releases of greenhouse gases, this could compromise proposed mitigation efforts for controlling the carbon cycle," he says.


The article, Sensitivity of the Carbon Cycle in the Arctic to Climate Change, was published online today in Ecological Monographs. The coordinating lead author is David McGuire, USGS, and the co-authors include internationally renowned scientists from Canada, Germany, Sweden, and the United States. This study was sponsored by the Arctic Monitoring and Assessment Program, the Climate in the Cryosphere Program, and the International Arctic Science Committee.

Tuesday, September 8, 2009

WWF Fears on Arctic Melt


I certainly do not go to these sources for creditable scientific interpretation. They have long since succumbed to their biases and often publish nonsense. This limits them to their core believers and provides no leverage anywhere else. This I find unfortunate because I believe the mission of either is praiseworthy but execution is in the hands of propagandists rather that anyone capable of making an impact.

The present argument is attempting to promote the modest decadal warming in the Arctic into something much more. It isn’t. First of the net change is a mere degree. This reflects a very modest increase in the vastly larger southern latitudes. In fact it is a down grade from earlier less accurate measures. The point that I want to make is that the areal extent of the Arctic is possibly a seventh of the areal extent of the lower latitudes. Thus we are possibly looking at a seventh of a degree change from that quarter.

The warming of the Arctic was about the only credible indicator we had of a warmer northern hemisphere. It halted two years ago just after a pretty good dump of heat into the Arctic by winds. One could say that the rest of the hemisphere is now trying to warm up again.

This article rehashes the usual global warming story. However, the ice pack is a result of the minor fact that the sun fails to provide heat for a few months. There will always be an ice pack even if the Arctic summer is tropical. If we are really lucky, we may get rid of most of it for a week or two.


Arctic thaw threatens much of world: WWF report

http://www.terradaily.com/reports/Arctic_thaw_threatens_much_of_world_WWF_report_999.html

This part is an insert and included with another picture of the north

Greenland glaciers melting faster than ever: NGO

Greenland's glaciers are melting into the sea faster than ever before, the environmental pressure group Greenpeace claimed on Wednesday. Glaciers move when melting occurs from the effects of global warming, causing masses of ice to slide into fjords and the sea. Greenland's Helheim glacier, which measures six kilometres wide (four miles) and is one kilometre thick, moves about 25 metres (yards) a day, Greenpeace said in a statement. The group said that is twice as fast as when its Arctic Sunrise vessel last visited Greenland in 2005. The speed of the other major glacier in Greenland, Kangerdlugssuaq, is even more dramatic. It moves some 38 metres a day or 14 kilometres a year, Greenpeace said. "Kangerdlugssuaq Glacier is probably the world's fastest moving glacier," said Dr. Gordon Hamilton, from the University of Maine's Climate Change Institute. Hamilton is a member of this year's Greenpeace expedition currently inspecting the glaciers in the north and east of the Danish territory. The group's Arctic Sunrise vessel left for the region at the end of June and is due to complete its mission at the end of September. The two glaciers produce 10 percent of Greenland's ice output into the North Atlantic. Glaciers that shed their ice cause sea levels to rise. Sea levels are currently on the increase by three millimeters a year, according to Greenpeace, and pose a serious threat to people living on islands or in coastal regions.


Main Text

by Staff Writers
Geneva (AFP) Sept 2, 2009

Global warming in the Arctic could affect a quarter of the world's population through flooding and amplify the wider impact of
climate change, a report by environmental group WWF said Wednesday.

Air temperatures in the region have risen by almost twice the global average over the past few decades, according to the peer-reviewed scientific report.

That is not just down to melting the polar ice pack, a major cooling agent for global weather patterns and reflector of sunlight.

It is also linked to the release of more of the greenhouse gases responsible for global warming that are naturally trapped in frozen soil, it claimed.

"What this report says is that a warming Arctic is much more than a local problem, it's a global problem," said Martin Sommerkorn, senior climate change advisor on the WWF's Arctic Programme.

"Simply put, if we do not keep the Arctic cold enough, people across the world will suffer the effects," he warned.

The combination of thawing Arctic sea ice and
melting ice sheets in Greenland and West Antarctica was likely to raise global sea levels by about 1.2 metres (four feet) by 2100, more than previously thought, according to scientists commissioned by the WWF for the report.

"The associated flooding of coastal regions will affect more than a quarter of the world's population," the WWF said.

Scientists have expressed concern in recent years about the now visible melting of the Arctic region, to the extent that some have predicted virtually ice-free summers there this century.

The full impact of polar melting has yet to be taken into account by the Intergovernmental Panel on Climate Change, the scientific reference for world
climate predictions, as reliable observations have only started to emerge in recent years.

Sommerkorn said the melting was already having an effect on the weather in the northern hemisphere, such as drier conditions in Scandinavia or the southwest of North America, or more humid Mediterranean winters.

However some climatologists at the World Climate Conference here urged caution about such short-term judgments, while acknowledging the major long-term influence of Arctic melting on the world's climate.
"We see that summer sea ice is likely to disappear by 2060," said Vicky Pope, head of climate change advice at Britain's Met Office.

"But I don't think we understand the physics yet," she added, pointing to possible natural variability to account for recent local weather patterns.

The WWF report concluded that melting sea ice and the release of pockets of greenhouse gases -- carbon dioxide from thawing permafrost and methane seeping from the depths of the warming Arctic Ocean -- would also fuel disruption to atmospheric and ocean currents much further afield.

Arctic permafrost stores twice as much carbon as contained in the atmosphere, acording to the WWF. Some 90 percent of near surface permafrost in the Arctic could disappear by the end of the century, the report found.

That trend could significantly accelerate global warming and force a shift in emissions targets, Sommerkorn told journalists.

"If we allow the Arctic to get much warmer it is really doubtful whether we will be able to keep the
Arctic climate feedbacks under control," he said.

UN Secretary General Ban Ki-moon, who is due at the conference later this week, on Wednesday urged world leaders to act now to halt global warming, after seeing first-hand its effects in the Arctic during a visit to Norway.

"The Arctic is similar to sending a canary into a coalmine -- this is a danger warning for the global climate," he said.

World leaders will gather at a UN
climate

summit in Copenhagen in December to try and seal a new international accord on fighting climate change.

Monday, May 4, 2009

Clathrate Stable through Younger Dryas

This work is the sort of news that perhaps a few would understand. We have unbelievable amounts of methane sequestered in the form of clathrates. This is a methane water ice combination that shows up in permafrost and deep enough in the ocean, usually on the continental shelf. It represents methane accumulation that encompasses millions of years and the volumes are naturally mind boggling. It is the ultimate reserve of fossil fuels.

It turns out to be difficult to recover and this article confirms nicely that Mother Nature has problems getting it out also. It may not be as safely sequestered as granite but it is doing a good imitation.

Rather importantly, this work has shown that during a period of unusual methane concentration and violent climate change, that the methane did not originate from the clathrates. They are still there but they are not now anyone’s first suspect.
Like most, I had assumed that the sharp increase in atmospheric methane was likely forced by the release of this particular form of trapped methane.
This work has removed that source from consideration and leaves us with the ample supply been produced by wetlands. The excess methane may have been associated with an excessive increase in boreal forest wetlands been created as the ice rapidly retreated. It obviously takes a long time for a freshly started muskeg to stabalize to the conditions that are now present and it is reasonable to conjecture that this process is methane producing.

Greenland Methane Danger Far Less Than Feared

by Staff Writers
Canberra, Australia (SPX) Apr 28, 2009

http://www.terradaily.com/reports/Greenland_Methane_Danger_Far_Less_Than_Feared_999.html

Ice core research has revealed that a vast, potential source of the potent greenhouse gas, methane, is more stable in a warming world than previously thought. Based on international research published in Science, the finding includes Australian contributions from CSIRO and the Australian Nuclear Science and Technology Organisation (ANSTO)

Wetlands in the tropics and emerging from under receding Northern Hemisphere glaciers have been considered the primary source of rising atmospheric methane in a warming world. But scientists have known of another potential source.

Massive quantities of methane are locked away in permafrost and in the ocean floors as methane clathrate - an ice-like material which can return to gas if temperatures increase or pressures drop. Just a 10 per cent release of methane would have the equivalent impact on global warming of a ten-fold increase in carbon dioxide concentration.

So began a US, New Zealand and Australian research project to understand ice core records spanning hundreds of thousands of years, profiling periods of high-methane increase and focusing on the Younger Dryas period. The cause of the large increase in methane 12,000 years ago as the Earth warmed and the Younger Dryas ended has been a source of much debate among scientists.

"The result is a good news outcome for climate scientists monitoring greenhouse gases and investigating the likely sources of methane in a warming world," says CSIRO's Dr David Etheridge, from the Centre for Australian Weather and Climate Research who helped show how the air could be extracted from polar ice to measure past methane changes and identify their causes.

"There are vast stores of methane clathrates beneath the ocean and in permafrost and there is evidence that millions of years ago release from these storages caused significant climate change, although none in more recent times.

"The objective of the research was to determine how stable the clathrate methane stores were as the Earth warmed rapidly from its last glacial state and whether clathrates might be a source of future climate change as global temperatures rise."

Dr Andrew Smith, from ANSTO, studied the source of methane by using a technique called accelerator mass spectrometry to detect individual radiocarbon atoms from ancient atmospheric methane samples over the Younger Dryas period.

"Radiocarbon provided the key insight to decide whether the extra methane was derived from clathrates or from wetlands," Dr Smith says.

"A multi-disciplinary team of scientists from the US Scripps Institution of Oceanography, New Zealand's National Institute of Water and Atmosphere, and from Australia's ANSTO and CSIRO combined their resources to tackle this challenging project."

The project involved years of field-work in West Greenland where scientists accessed samples located in 'outcropping' ice, a cross-section of ice formed over tens of thousands of years that is exposed at the surface. A tonne of ice was excavated to provide sufficient air from trapped bubbles for each measurement of the methane carbon isotopes.
Extremely sensitive analysis was required because of the low concentration of methane in air and because only about one trillionth of that methane contains radiocarbon - the carbon-14 isotope that is the key indicator of clathrate emissions. The analysis was undertaken at ANSTO in southern Sydney.

The methane isotope change accompanying the jump in concentration confirmed that the emission was not from clathrates, but from ecological sources such as wetlands.

"We know that emissions of methane are increasing now and that some sources might emit even more with warming, causing a positive climate feedback, or amplification. But this finding suggests that the clathrate source is less susceptible than recently feared," Dr Smith says.

Wednesday, February 18, 2009

Climate Changing NOx

I am showing this item as a reminder of the not well known fact that huge amounts of methane and other gases are locked up in the permafrost and as usual much is made of the green house gas potential.

I have seen the methane factor beaten on before in regard to this same issue and again it is largely irrelevant.

Firstly CO2 is an end product of the carbon oxidation process and it is heavy enough to hang around looking for a plant to absorb it. It is a real possible factor to consider for greenhouse gas fame.

Methane however, puts on its rocket pack and heads straight for the troposphere, unless it happens to be oxidized into CO2 first. If there is ever an accumulation please do not light a match. Actual maps of land based methane show it disappearing downwind and offshore as it escapes to the troposphere.

And now someone wants to get excited over NO2. Firstly, there isn’t much of it and likely the frozen conditions helped in preserving it. If it does get free, it will immediately combine with any available water molecule and produce nitric acid and reduce something tougher. Recall that lightning produces millions of tons of this stuff to fertilize our fields. Perhaps we need to launch an initiative to stop lightning to prevent global warming.

I think they are finally running out of ideas.

And by the way, how do we know exactly how much CO2 is absorbed by the ocean and how do we measure variability? This article suggests a degree of precision that seems to me to be plainly impossible.

Climate change: 'Feedback' triggers could amplify peril

by Staff Writers
Paris (AFP) Feb 15, 2009

New studies have warned of triggers in the natural environment, including a greenhouse-gas timebomb in Siberia and Canada, that could viciously amplify global warming.

Thawing subarctic tundra could unleash billions of tonnes of gases that have been safely stored in frosty soil, while oceans and forests are becoming less able to suck carbon dioxide (CO2) out of the atmosphere, according to papers presented this weekend.

Together, these phenomena mean that more heat-trapping gases will enter the atmosphere, which in turn will stoke global warming, thrusting the machinery of
climate change into higher gear.

Researchers in Finland and Russia discovered that nitrous oxide is leaking into the air from so-called "peat circle" ecosystems found throughout the tundra, a vast expanse of territory in higher latitudes.

CO2 and methane account for the lion's share of the gases that have driven global temperatures inexorably higher over the last century.

Nitrous oxide, or N2O, is far less plentiful in volume, but 300 times more potent as a greenhouse gas than CO2. It accounts for about six percent of total global warming, mainly due to a shift toward chemical-intensive agriculture.

In experiments near the Russian city of Vorkuta, Pertti Martikainen of the University of Kuopio in Finland and colleagues found that N2O leaked as a result of cryoturbation, a process that occurs when frozen soil is thawed and then refreezes.

"There is evidence that warming of the Arctic will accelerate cryoturbation, which would lead to an increased abundance of peat circles in the future," said their paper, published on Sunday in the journal Nature Geoscience.

"This would increase N20 emissions from tundra, and therefore a positive feedback to climate change."

Research presented Saturday at a meeting of the American Association for the Advancement of Science (AAAS) in Chicago suggested that the frozen soil of the tundra stored far more greenhouse gas that previously thought.
"Melting permafrost is poised to be a strong foot on the accelerator pedal of atmospheric CO2," said Chris Field, a professor at Stanford and a top scientist on the United Nation's Intergovernmental Panel for Climate Change (IPCC).

"The new estimate of the total amount of carbon that's frozen in permafrost soils in on the order of 1,000 billion (one trillion) tonnes," he said.

By comparison, the amount of CO2 that has been released through the burning of fossil fuels since the beginning of the Industrial Revolution is around 350 billion tonnes.

The greenhouse gases in the tundra, which also includes methane, come from the decayed remains of vegetation that died long ago.

Meanwhile, new research on the Southern Ocean surrounded Antarctica suggest that the sea, a vital "carbon sink," is sucking up less CO2 than before.

Nicolas Metzl, a researcher at the French National Research Institute, said fierce winds -- aggravated by climate change and gaps in the ozone layer -- were churning the sea, which brought CO2 to the surface and released it into the air.

This adds to previous research that points to the sea's drooping effectiveness as a carbon sponge, he said.

"Today, human activity injects about 10 billion tonnes of CO2 per year into the atmosphere, compared to around six billion in the early 1990s," said Metzl.

"Before we had an ocean that captured some two billion tonnes -- about a third. Today we are below two billion tonnes," less than a fifth of the total, he added.

earlier related report

Climate change could be even worse than feared

It seems the dire warnings about future devastation sparked by global warming have not been dire enough, top climate scientists warned Saturday.
It has been just over a year since the Nobel-winning Intergovernmental Panel on Climate Change (IPCC) published a landmark report warning of rising sea levels, expanding deserts, more intense storms and the extinction of up to 30 percent of plant and animal species.

But recent climate studies suggest that report significantly underestimates the potential severity of global warming over the next 100 years, a senior member of the panel warned.

"We are basically looking now at a future climate that is beyond anything that we've considered seriously in climate policy," said Chris Field, who was a coordinating lead author of the report.

"Without effective action, climate change is going to be larger and more difficult to deal with than we thought."

Fresh data has shown that greenhouse gas emissions have grown by an average of 3.5 percent a year from 2000 to 2007, Field told reporters at a meeting of the American Association for the Advancement of Science.

That's "far more rapid than we expected" and more than three times the 0.9 growth rate in the 1990's, he said.

While increased economic activity could have contributed to the growth in emissions, Field said it appears as though the bulk of the growth is "because developing countries like China and India saw a huge upsurge in electric power generation, almost all of it based on coal."

Further complicating the problem is that higher temperatures could thaw the Arctic tundra and ignite tropical forests, potentially releasing billions of tons of carbon dioxide that has been stored for thousands of years.

That could raise temperatures even more and create "a vicious cycle that could spiral out of control by the end of the century."

"We don't want to cross a critical threshold where this massive release of carbon starts to run on autopilot," said Field, a professor of biology and of environmental Earth system science at Stanford University.

The amount of carbon that could be released is staggering.

Since the beginning of the Industrial Revolution an estimated 350 billion tonnes of carbon dioxide (CO2) have been released through the burning of fossil fuels.

The new estimate of the amount of carbon stored in the Arctic's permafrost soils is around 1,000 billion tonnes. And the Arctic is warming faster than any other part of the globe.

Several recent climate models have estimated that the loss of tropical rainforests to wildfires, deforestation and other causes could increase the concentration of carbon dioxide in the atmosphere from 10 to 100 parts per million by the end of the century.

The current level is about 380 parts per million.

"Tropical forests are essentially inflammable," Field said. "You couldn't get a fire to burn there if you tried. But if they dry out just a little bit, the result can be very large and destructive wildfires."

Recent studies have also shown that global warming is reducing the ocean's ability to absorb carbon by altering wind patterns in the Southern Ocean. Faster winds blow surface out of the way, causing water with higher concentrations of carbon dioxide to rise to the surface.

Sea levels are also rising faster than previously estimated as ocean temperatures warm and melting ice in mountain glaciers and at the poles flows into the ocean, warned Anny Cazenave, of France's Centre National d'Etudes Spatiales.

Fresh analysis using satellite imaging has shown that in the past 16 years, average sea levels have risen at a rate that is twice as fast as the last century: more than three millimeters a year.

Some regions have seen levels rise as much as one centimeter a year, Cazenave told reporters.

The expanding use of biofuels could also contribute to global warming because farmers are cutting down and burning down tropical forests to plant crops, said Holly Gibbs of Stanford University.

"If we run our cars on biofuels produced in the tropics, chances will be good that we are effectively burning rainforests in our gas tanks," she warned.

Monday, September 17, 2007

Changing Arctic Ocean

In my last post, I showed that we have at most a decade before the last of the long term sea is gone and no longer a factor. What difference will it make?

The important change will be in the amount of summer heat absorption in the Arctic Ocean. Up to very recently, this factor was negligible since the Sea remained covered with minor late season clearances. This year, half the Arctic is clear. And the other half will mostly clear in the next decade. This will be additionally stabilized by the sharp increase in solar energy absorption in the top layer of water.

What I am saying, is that once the ice is gone, the annual reestablishment of sea ice cover will be more difficult. The water will be slightly warmer and will take longer to establish its annual thickness.

Remember that it took 32 calories to melt or freeze the ice in the first place. If all this unused energy goes into warming the arctic waters, then Our sea ice cover will behave a lot like the sea ice cover in Hudson Bay providing perhaps a four month long clear sailing environment.

It will still be too cold to generate much evaporation, so there should be little change for the land based ice sheets. This conforms to the data provided by the drill cores that go back over 15,000 years. In fact, the only break in that data continuity came 12500 years ago and is a principle marker for the Pleistocene nonconformity. It became dryer.

This also suggests open seas during the summer months of the Bronze Age and their near reemergence in the early fifteenth century. It also loudly begs the question of what mechanism cooled the northern Hemisphere, or more appropriately what cooled the surface waters of the gulf stream?

A previous post suggested that the mechanism was an injection of cold water from the Antarctic. We just have not figured it all out yet. I think though that we should be prepared for a nasty surprise there. The open question in my mind is whether we now have any evidence to support a four hundred year chilling cycle for the Atlantic? It may be more random than that, but it likely exists.

It has only taken 400 years to recover from the little ice age. Yet almost 2500 years had passed since the collapse of the Bronze Age optimum. Surely someone noticed? My point is that as far as we can determine, most of those 2500 years were chilly. We could actually be dead wrong here and the climate could have been generally warmer throughout and the real anomaly is the recent little ice age.

Time to look at those tree rings and pollen samples in transition areas to get a much refined climate proxy.

Otherwise, with the current regime, We know that the permafrost line will shift north somewhat, and the tree line will also move north. It is hard to see how this will effect humanity very much since few of us like to live in alpine like conditions. The short summers will remain the same and be just a little warmer. And there are many better places to grow potatoes.

Local coastal agricultural enclaves will be possible, just like those old Vikings in Greenland. Otherwise, a quick trip to Churchill will inform you of likely future conditions in the high Arctic.

Certainly, once the long term ice is gone, the shipping season will open right up although I am sure everyone will plan on a September crossing. The polar bears will be able to treat the whole Arctic the same way they treat Hudson Bay with a much longer hunting season. I would also expect an explosion in the Arctic biomass in general since there will be a season in which the ocean receives sufficient solar energy for all forms of plankton and the like.

The high arctic will still be a desert on land, but the ocean could easily become the globe's larder if managed well.